Change the way private key and cert are embedded.

OpenSSL seems to serialize bigints as signed value, which means the ECC
key may end up being 33 bytes instead of the 32 bytes we're expecting,
causing build to fail.
The shell script extraction is now replaced by a build.rs script that
uses OpenSSL to extract the content and do sanity checks.
Forcing generating cryptographic materials now always generate a key and
a certificate (useful to compile/flash multiple keys without them being
considered as clones). The self-signed CA is left untouched.

.gitignore

@@ -3,5 +3,3 @@ Cargo.lock
 
 # Prevent people from commiting sensitive files.
 crypto_data/
-src/ctap/key_material.rs
-

Cargo.toml

@@ -26,6 +26,9 @@ panic_console = ["libtock/panic_console"]
 [dev-dependencies]
 elf2tab = "0.4.0"
 
+[build-dependencies]
+openssl = "0.10"
+
 [profile.dev]
 panic = "abort"
 lto = true # Link Time Optimization usually reduces size of binaries and static libraries

build.rs

+// Copyright 2019 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+extern crate openssl;
+
+use openssl::asn1;
+use openssl::ec;
+use openssl::nid::Nid;
+use openssl::pkey::PKey;
+use openssl::x509;
+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::Path;
+
+fn main() {
+    println!("cargo:rerun-if-changed=crypto_data/opensk.key");
+    println!("cargo:rerun-if-changed=crypto_data/opensk_cert.pem");
+
+    let out_dir = env::var_os("OUT_DIR").unwrap();
+    let priv_key_bin_path = Path::new(&out_dir).join("opensk_pkey.bin");
+    let cert_bin_path = Path::new(&out_dir).join("opensk_cert.bin");
+    let aaguid_bin_path = Path::new(&out_dir).join("opensk_aaguid.bin");
+
+    // Load the OpenSSL PEM ECC key
+    let ecc_data = include_bytes!("crypto_data/opensk.key");
+    let pkey = ec::EcKey::private_key_from_pem(ecc_data)
+        .ok()
+        .expect("Failed to load OpenSK private key file");
+
+    // Check key validity
+    pkey.check_key().unwrap();
+    assert_eq!(pkey.group().curve_name(), Some(Nid::X9_62_PRIME256V1));
+
+    let mut priv_key = pkey.private_key().to_vec();
+    if priv_key.len() == 33 && priv_key[0] == 0 {
+        priv_key.remove(0);
+    }
+    assert_eq!(priv_key.len(), 32);
+
+    // Create the raw private key out of the OpenSSL data
+    let mut priv_key_bin_file = File::create(&priv_key_bin_path).unwrap();
+    priv_key_bin_file.write_all(&priv_key).unwrap();
+
+    // Convert the PEM certificate to DER and extract the serial for AAGUID
+    let input_pem_cert = include_bytes!("crypto_data/opensk_cert.pem");
+    let cert = x509::X509::from_pem(input_pem_cert)
+        .ok()
+        .expect("Failed to load OpenSK certificate");
+
+    // Do some sanity check on the certificate
+    assert!(cert
+        .public_key()
+        .unwrap()
+        .public_eq(&PKey::from_ec_key(pkey).unwrap()));
+    let today = asn1::Asn1Time::days_from_now(0).unwrap();
+    assert!(cert.not_after() > today);
+    assert!(cert.not_before() <= today);
+
+    let mut cert_bin_file = File::create(&cert_bin_path).unwrap();
+    cert_bin_file.write_all(&cert.to_der().unwrap()).unwrap();
+
+    let mut aaguid_bin_file = File::create(&aaguid_bin_path).unwrap();
+    let mut serial = cert.serial_number().to_bn().unwrap().to_vec();
+    serial.resize(16, 0);
+    aaguid_bin_file.write_all(&serial).unwrap();
+}

src/ctap/key_material.rs

+// Copyright 2019 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+pub const AAGUID: [u8; 16] = *include_bytes!(concat!(env!("OUT_DIR"), "/opensk_aaguid.bin"));
+
+pub const ATTESTATION_CERTIFICATE: &[u8] =
+    include_bytes!(concat!(env!("OUT_DIR"), "/opensk_cert.bin"));
+
+pub const ATTESTATION_PRIVATE_KEY: [u8; 32] =
+    *include_bytes!(concat!(env!("OUT_DIR"), "/opensk_pkey.bin"));

tools/gen_key_materials.sh

@@ -36,6 +36,7 @@ generate_crypto_materials () {
     exit 1
   fi
 
+  force_generate="$1"
   mkdir -p crypto_data
   if [ ! -f "${ca_priv_key}" ]
   then
@@ -60,12 +61,12 @@ generate_crypto_materials () {
       -sha256
   fi
 
-  if [ ! -f "${opensk_key}" ]
+  if [ "${force_generate}" = "Y" -o ! -f "${opensk_key}" ]
   then
     "${openssl}" ecparam -genkey -name prime256v1 -out "${opensk_key}"
   fi
 
-  if [ ! -f "${opensk_cert_name}.pem" ]
+  if [ "${force_generate}" = "Y" -o ! -f "${opensk_cert_name}.pem" ]
   then
     "${openssl}" req \
       -new \
@@ -83,87 +84,4 @@ generate_crypto_materials () {
       -out "${opensk_cert_name}.pem" \
       -sha256
   fi
-
-  local cert_mtime=$(stat --printf="%Y" "${opensk_cert_name}.pem")
-  local rust_file_mtime=0
-  # Only take into consideration the mtime of the file if it exists and if we're not forcing
-  # the rust file to be re-generated.
-  if [ -f "${rust_file}" -a "x$1" != "xY" ]
-  then
-    rust_file_mtime=$(stat --printf="%Y" "${rust_file}")
-  fi
-  if [ $cert_mtime -gt $rust_file_mtime ]
-  then
-    local cert_size=$("${openssl}" x509 \
-      -in "${opensk_cert_name}.pem" \
-      -outform der 2>/dev/null \
-      | wc -c)
-    local cert_serial_hex=$("${openssl}" x509 \
-      -in "${opensk_cert_name}.pem" \
-      -noout \
-      -serial \
-      | cut -d'=' -f2)
-    # Pad with zeroes in case the serial is too short. We don't care if the
-    # serial is longer than 32 characters as we will only process the first 32
-    # characters in the loop later.
-    cert_serial_hex="${cert_serial_hex}00000000000000000000000000000000"
-
-    # Create header
-    echo "// This file had been generated by OpenSK deploy.sh script" > "${rust_file}"
-    echo "" >> "${rust_file}"
-
-    echo "pub const AAGUID: [u8; 16] = [" >> "${rust_file}"
-    for i in `seq 0 2 30`
-    do
-      echo -n "0x${cert_serial_hex:$i:2}, " >> "${rust_file}"
-    done
-    echo "" >> "${rust_file}"
-    echo "];" >> "${rust_file}"
-    echo "" >> "${rust_file}"
-
-    echo "pub const ATTESTATION_CERTIFICATE: [u8; ${cert_size}] = [" >> "${rust_file}"
-    "${openssl}" x509 \
-      -in "${opensk_cert_name}.pem" \
-      -outform der 2>/dev/null \
-      | xxd -i >> "${rust_file}"
-    echo "];" >> "${rust_file}"
-    echo "" >> "${rust_file}"
-
-    # Private key is tricky to extract as we want the raw value and not the DER encoding
-    # Example output of openssl ec -in file.key -noout -text:
-    # read EC key
-    # Private-Key: (256 bit)
-    # priv:
-    #     47:b3:58:b8:f0:09:1d:72:b1:03:34:62:9a:c7:b2:
-    #     b2:e1:06:28:15:69:d4:82:b5:4e:21:6d:98:bf:65:
-    #     98:34
-    # pub:
-    #     04:32:84:a1:3c:90:db:3f:db:d7:fb:ff:e9:00:c8:
-    #     8a:a1:79:2e:95:2e:7c:86:ec:19:03:97:6e:7c:d6:
-    #     67:eb:28:56:f1:d8:dd:cb:ae:ce:b9:cb:e4:6d:9d:
-    #     1d:76:96:fc:48:9b:2d:d5:80:86:04:3d:f9:fe:6c:
-    #     f3:9a:45:bc:b1
-    # ASN1 OID: prime256v1
-    # NIST CURVE: P-256
-    #
-    # The awk script starts printing lines after seeing a line starting with
-    # "priv:" and stops printing as soon as it reaches a line that doesn't start
-    # with a space.
-    # The sed script then converts the output into a proper hex-encode byte
-    # array by replacing the initial spaces on each line with "0x", replacing
-    # the semicolons at the end of each line by commas and replacing all
-    # remainging semicolons by ". 0x".
-    echo "pub const ATTESTATION_PRIVATE_KEY: [u8; 32] = [" >> "${rust_file}"
-    "${openssl}" ec \
-      -in "${opensk_key}" \
-      -noout \
-      -text 2>/dev/null \
-      | awk '/^priv:/{p=1;next}/^[^ ]/{p=0}p' \
-      | sed -e 's/^  */0x/;s/:$/,/;s/:/, 0x/g' >> "${rust_file}"
-    echo "];" >> "${rust_file}"
-    echo "" >> "${rust_file}"
-
-    # If the tool is installed, prettify the file. It will catch syntax errors earlier.
-    which rustfmt > /dev/null 2>&1 && rustfmt "${rust_file}"
-  fi
 }